Method of making copperas



Apr-i1 24, 1928.

H. C. STEWART METHOD 0F MAKING COPPERAS Filed May 5, 1925 'Ll {HI'I'I INVENTOR.

A TTORNE Y.

Patented Apr. '24, 1928.

UNITED STATES PATENT OFFICE.

HENRY CARLISLE STEWART, F PHILADELPHIA, PENNSYLVANIA, ASSIGNOE TO THE WESTHORELAND CHEMICAL COLOR COMPANY OF PHILADELPHIA, PENNSYL- `VANIA, A CORPORATION 0F PENNSYLVANIA.

I METHOD or MAKING corrnnas.

Application led Hay 3, 1 923. Serial No. 636,487.

Inthe manufacture of copperas (FeSO,.7H2O) one of the sources of supply of ferrous sul- 5 phate in solution consists of the sludge produced asa by-product or waste product resulting from the cleansing of scale from iron wire, rods, sheets, etc., produced by the placing of such iron wire, rods, sheets, etc., in tanks or vats containing a pickling liquor consisting of sul huric acid and water. The scale is disso ved in and combines with the sulphuric acid to form what is known in the trade as sludge, which contains ferrous'sulphate and usually some free sulphuric acid. In ractice it is desirable that the' plant for tie manufacture of copperas shall be situated in such proximity to such cleansing plant or apparatus thatthe sludge7` may be conducted directlyto the apparatus employed in the manufacture of copperas. This sludge usually contains all sorts of impurities and foreign matter which should be removed. It is` therefore one of the objects of my invention to rovide a method of treatment of the slu ge whereby impurities in solid 4form may be removed therefrom.

A further object of the invention is to whereby the production of a purer roduct than heretofore has beenfound to e commercially practicable may be effected.

A still further object ofthe invention is to provide a method which is more efficient and which may be practiced and carried outl more economically thanv the methods heretofore employed. l A still further object is to provide a method whereby crystallization of the ferrous sulphate from its solution mayl be ef fected ,during transit: or delivery into the crystallization tank ortanks. l Other `ob'ects 'd advantages of the invention will be pointed out in the detailed description thereof which follows or will be apparent from such description,

- .Although my invention is not dependent -upon any particular character or construction of apparatus, I have shown in thev accnmpanym drawing, for theA sake of facilitating t e escription of the method and its operation,v one form of apparatus which may provide a method of producing copperasl be employed in the Ycarrying out or practicing of the method.

In the said drawing:

Fig. 1 is a view in sectional elevation 0f an apparatus which ma be employed in the carrying out of my lnvention;l and Fig., 2 is a view in 'transverse section taken on the line 2--2 of Fig. 1.

Referring to the drawing: 1 designates a pipe or conduit by means of 4which the sludge is delivered into a filter 2 consistin-g or filtros (silica) bricks which are sufficiently porous to allow the, liquid of the sludge to flow therethrough. Impurities in the form of solids, however, are retained -within the filter and may afterwards be removed. This sludge is delivered from the filter 2 into a tank 3 which may7 contain Y scrap iron, as indicated at 4, which re-acts with an sulphuric acid which may be present. T ie solution is conducted from vthe i tank 3 by means of a pumpv 5 and by line 6 -to a tank 10 containing steam coils 11 therein by means of which the said solution, while in the said tank, ma be boiled so as to concentrate vthe solutlon. This tank also contains scrap iron, as indicated at 12, which re-acts with anyfree sulphuric acid which may bepresent. After having been boiled to increase the concentration thereof from approximately 24 Baum tov 35g to 40 Baume the solution is drawn ofi' from `the tank 10 through a valve controlled pipe 15, preferably though not necessarily. into la filter 16 similar to that at 2 and from vthe latter is dischargedinto a settling and c001- ing tank 17. The solutionvis allowed to remain in this tank for several hours until it has cooled. A certain amount of settling also takes lace in this tank. Afterhavinor settled an cooled the said solutonis-'delivered into troughs, one of whichiisindL. cated at 20, from whichit is discharged into a tank 21.

.In order to effect crystallization of a large proportion of the ferrous sulphate from its solution the stream of the said solution, as it is discharged from the trough 20, is met bv a stream of air, as indicatedat 22, discharged from a pipe 23. The airis supplied by means ofany suitable air pump, blower or compressor. The nozzle 24 from which the airis discharged should be of a ioo width equal to the width of the stream of solution which is discharged from the trough 20. The said nozzle is also inclined so that the stream of air 22 discharged therefrom will travel in a direction transversely of the falling stream of the solution. result the lair is thorough] intermingled with the liquid stream, brea ing it up info fineA particles. By thus causing a stream of air to strike the stream of 1i uid andbreaking the latterup as'idescribe instantaneous crystallizationI of a large proportion of the ferrous sulphate is effected. The crystals produced are of needle-like formation. YThis product is known as needle copperas.

lAfter a tank has been charged the portion.

of the solution which has not been crystallized and which still remains in liquid form may be removed to another tank and further crystallization of the ferrous sulphate therefrom effected in the usual and well known manner, If preferred, however, the said remaining li uid portion of the solution may be returned y siphonic action through the i pipe 25 to the tank v3 so that such solution may again pass through the c cle of treatment as hereinbefore describe The copperas inthe form of these needle crystals is removed from the tank and allowed to dry'y for a number of. hours, say twenty-four hours, and is readyfor shipment or for use. Y

Withina day or so after the removal'of the needle crystals of copperas from the said tank these needles have become dry and assume the shapefof small pellets. This has beenV found to be a form best suited for the subsequent treatment of the said copperas inthe incinerating processes employed in the conversion thereof into iron oxide for use in the manufacture of paints or other products.

Having thus described my inv'entom, what 7 I claim and desire to secure by Letters Patent is: t 1. The method of producing copperas from As a.

a solution of ferrous sulphate of a densityj stream and projecting a stream of air against and transversely of the said'stream of solution to atomize and effect crystallization of the ferrous sulphate therein.

2. The method of producing copperas from a vsolution .of ferrous sulphate of a density of 35 to 40 Baume, which comprises the discharge ofl said solution of ferrous sul-A phate in the'form of a wide thinl'stream and projecting a stream of air of substantially the same Width against and transversely of said stream to atomize the'same and effect crystallization of a portion ofthe ferrous sulphate held in solution.

3. The method of producing c'opperas from 'a solution of ferrous sulphate of a density of 35 to 40 Baume, which comprises the discharge of a stream of said solution, discharging a stream of air against and transversely of the said stream to break the same up. into small `particles and thereby effect crystallization of a portion ofthe ferrous sulphatein solution, collecting the crystal lized and uncrystall-ized portions within a tank, and thereafter separating the two.

4, The method of lproducing copperas, which comprises lthe filtration of a sludge containing ferrous sulphate in solution, thereafter boiling said solution to effect concentration thereof-to a density of 35 to 40 Baum, cooling the same, delivering` the cooledsolution into a conduit, discharging thesame from said conduit in .the form of a stream, and discharging a stream of air under pressure into the saidstream of the solution to break' the same up and effect crystallization of a portion of the ferrous sul hate therein.

n testimony that I claim the foregoing as' my invention, I have hereunto signed my name thisl 1st day of Ma A. D., 1923.

' HENRY CARLIS E STEWART.

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